Hedgehog/Gli promotes epithelial-mesenchymal transition in lung squamous cell carcinomas

IQGAP3 activates Hedgehog signaling to confer stemness and metastasis via up-regulating GLI1 in lung cancer

Lung cancer ranks as the most prevalent malignant neoplasm worldwide, contributing significantly to cancer-related mortality. Stemness is a well-recognized factor underlying radiotherapy resistance, recurrence and metastasis in non-small-cell lung cancer (NSCLC) patients. Our prior investigations have established the role of IQ motif containing GTPase-activating protein 3 (IQGAP3) in mediating radiotherapy resistance in lung cancer, but its impact on lung cancer stemness remains unexplored. Our bioinformatics analysis results revealed a significant correlation between IQGAP3 and lung cancer stemness. Moreover, we found that IQGAP3 depletion in lung cancer cells resulted in reduced migration, invasion and sphere-forming capabilities. Through RNA sequencing, we identified GLI1 as a pivotal downstream effector of IQGAP3. The knockdown of IQGAP3 led to the downregulation of GLI1 mRNA and protein levels, which impeded the activation of the Hedgehog-GLI1 signaling pathway. Further, our results also indicated that GLI1 is the primary effector mediating IQGAP3's biological functions in lung cancer. These findings elucidate the role of IQGAP3 in promoting lung cancer stemness and metastasis through the Hedgehog pathway, facilitated by GLI1, highlighting the potential of IQGAP3 as a promising therapeutic target for lung cancer treatment.

Effects of Isoxazolyl Steroids on Key Genes of Sonic Hedgehog Cascade Expression in Tumor Cells

Activation of the Hedgehog (Hh) signaling pathway is often associated with the progression of various types of cancer. The purpose of study was to search for inhibitors of the Hh signaling pathway among eight compounds belonging to the group of isoxazolyl steroids. The evaluation of the effectiveness of the compounds was based on the analysis of their cytotoxicity, effect on the cell cycle, on the expression of key Hh-signaling-pathway genes (Ptch1, Smo, and Gli1) and putative target genes MMP-2 and MMP-9. Four compounds with the most pronounced cytotoxic effect were identified: compounds 1, 2 (HeLa cells) and 3, 4 (A549 cells). Compounds 1 and 2 significantly reduced the expression of the Ptch1, Smo, Gli1 genes, but had the opposite effect on MMP-2 gene expression: Compound 1 increased it, and compound 2 decreased it. Compounds 3 and 4 did not have a noticeable inhibitory effect on the expression of the Shh pathway receptors, but significantly inhibited MMP-2 and MMP-9 expression. Thus, it was shown that inhibition of the Shh signaling pathway by isoxazolyl steroids can have the opposite effect on MMPs gene expression, which is what should be taken into account in further studies of these compounds as therapeutic agents.

SALL4 upregulates brain-derived neurotrophic factor to mediate Hedgehog signaling to inhibit carboplatin sensitivity in colon adenocarcinoma

Aim: This study aimed to investigate the role of brain-derived neurotrophic factor (BDNF) in colon adenocarcinoma, specifically its impact on sensitivity to carboplatin.Methods: mRNA and clinical information of colon adenocarcinoma samples were obtained from TCGA database. Differential expression analysis, transcription factor prediction, gene set enrichment analysis were performed in silico. qRT-PCR, western blot, CCK-8 and CHIP assay were employed.Results: BDNF demonstrated high expression in colon adenocarcinoma. Silencing of BDNF enhanced carboplatin sensitivity, while exerting opposite effects on epithelial-mesenchymal transition (EMT). BDNF was enriched in Hedgehog (HH) signaling pathway. SALL4 was identified as an upstream regulator of BDNF. Upregulation of BDNF by SALL4 promoted EMT and inhibited carboplatin sensitivity.Conclusion: SALL4 promoted BDNF expression to facilitate the aggressive phenotypes of colon adenocarcinoma.

The comprehensive landscape of prognosis, immunity, and function of the GLI family by pan-cancer and single-cell analysis

The Hedgehog (Hh) signaling pathway has been implicated in the pathogenesis of various cancers. However, the roles of the downstream GLI family (GLI1, GLI2, and GLI3) in tumorigenesis remain elusive. This study aimed to unravel the genetic alterations of GLI1/2/3 in cancer and their association with the immune microenvironment and related signaling pathways. Firstly, we evaluated the expression profiles of GLI1/2/3 in different cancer types, analyzed their prognostic and predictive values, and assessed their correlation with tumor-infiltrating immune cells. Secondly, we explored the relationships between GLI1/2/3 and genetic mutations, epigenetic modifications, and clinically relevant drugs. Finally, we performed enrichment analysis to decipher the underlying mechanisms of GLI1/2/3 in cancer initiation and progression. Our results revealed that the expression levels of GLI1/2/3 were positively correlated in most cancer tissues, suggesting a cooperative role of these factors in tumorigenesis. We also identified tissue-specific expression patterns of GLI1/2/3, which may reflect the distinct functions of these factors in different cell types. Furthermore, GLI1/2/3 expression displayed significant associations with poor prognosis in several cancers, indicating their potential as prognostic biomarkers and therapeutic targets. Importantly, we found that GLI1/2/3 modulated the immune microenvironment by regulating the recruitment, activation, and polarization of cancer-associated fibroblasts, endothelial cells, and macrophages. Additionally, functional enrichment analyses indicated that GLI1/2/3 are involved in the regulation of epithelial-mesenchymal transition (EMT). Together, our findings shed new light on the roles of GLI1/2/3 in tumorigenesis and provide a potential basis for the development of novel therapeutic strategies targeting GLI-mediated signaling pathways in cancer.

Hedgehog signaling in tissue homeostasis, cancers, and targeted therapies

The past decade has seen significant advances in our understanding of Hedgehog (HH) signaling pathway in various biological events. HH signaling pathway exerts its biological effects through a complex signaling cascade involved with primary cilium. HH signaling pathway has important functions in embryonic development and tissue homeostasis. It plays a central role in the regulation of the proliferation and differentiation of adult stem cells. Importantly, it has become increasingly clear that HH signaling pathway is associated with increased cancer prevalence, malignant progression, poor prognosis and even increased mortality. Understanding the integrative nature of HH signaling pathway has opened up the potential for new therapeutic targets for cancer. A variety of drugs have been developed, including small molecule inhibitors, natural compounds, and long non-coding RNA (LncRNA), some of which are approved for clinical use. This review outlines recent discoveries of HH signaling in tissue homeostasis and cancer and discusses how these advances are paving the way for the development of new biologically based therapies for cancer. Furthermore, we address status quo and limitations of targeted therapies of HH signaling pathway. Insights from this review will help readers understand the function of HH signaling in homeostasis and cancer, as well as opportunities and challenges of therapeutic targets for cancer.

Combinations of PRI-724 Wnt/β-Catenin Pathway Inhibitor with Vismodegib, Erlotinib, or HS-173 Synergistically Inhibit Head and Neck Squamous Cancer Cells

The Wnt/β-catenin, EGFR, and PI3K pathways frequently undergo upregulation in head and neck squamous carcinoma (HNSCC) cells. Moreover, the Wnt/β-catenin pathway together with Hedgehog (Hh) signaling regulate the activity of cancer stem cells (CSCs). The aim of this study was to investigate the effects of the combinatorial use of the Wnt/β-catenin and Hh pathway inhibitors on viability, cell cycle progression, apoptosis induction, cell migration, and expression of CSC markers in tongue (CAL 27) and hypopharynx (FaDu) cancer cells. Co-inhibition of Wnt signaling with EGFR or PI3K pathways was additionally tested. The cells were treated with selective inhibitors of signaling pathways: Wnt/β-catenin (PRI-724), Hh (vismodegib), EGFR (erlotinib), and PI3K (HS-173). Cell viability was evaluated by the resazurin assay. Cell cycle progression and apoptosis induction were tested by flow cytometric analysis after staining with propidium iodide and Annexin V, respectively. Cell migration was detected by the scratch assay and CSC marker expression by the R-T PCR method. Mixtures of PRI-724 and vismodegib affected cell cycle distribution, greatly reduced cell migration, and downregulated the transcript level of CSC markers, especially POU5F1 encoding OCT4. Combinations of PRI-724 with erlotinib or HS-173 were more potent in inducing apoptosis.

The ULK3 kinase is a determinant of keratinocyte self-renewal and tumorigenesis targeting the arginine methylome

Epigenetic mechanisms oversee epidermal homeostasis and oncogenesis. The identification of kinases controlling these processes has direct therapeutic implications. We show that ULK3 is a nuclear kinase with elevated expression levels in squamous cell carcinomas (SCCs) arising in multiple body sites, including skin and Head/Neck. ULK3 loss by gene silencing or deletion reduces proliferation and clonogenicity of human keratinocytes and SCC-derived cells and affects transcription impinging on stem cell-related and metabolism programs. Mechanistically, ULK3 directly binds and regulates the activity of two histone arginine methyltransferases, PRMT1 and PRMT5 (PRMT1/5), with ULK3 loss compromising PRMT1/5 chromatin association to specific genes and overall methylation of histone H4, a shared target of these enzymes. These findings are of translational significance, as downmodulating ULK3 by RNA interference or locked antisense nucleic acids (LNAs) blunts the proliferation and tumorigenic potential of SCC cells and promotes differentiation in two orthotopic models of skin cancer.

Research progress on the role of fibroblast activation protein in diagnosis and treatment of cancer

Fibroblast activation protein (FAP) is a type II transmembrane protein, which is over-expressed in cancer-associated fibroblasts (CAFs). CAFs are tumor stromal cells that constitute a major component of cancer volume and are reportedly related to tumorigenesis, angiogenesis, metastasis, promotion of drug resistance and induction of tumor immunity. FAP is widely acknowledged as the signature protein of CAFs. At present, FAP inhibitors (FAPI) have achieved ideal results in tumor PET/computed tomography (CT) imaging. Theoretically, FAP-targeted drugs can inhibit tumor progression. Nonetheless, no satisfactory therapeutic effect has been observed so far, which has impeded their implementation in clinical practice. In this review, we describe the characteristics of FAP and its role in the occurrence and development of cancer. We also highlight the potential value of targeting FAP to improve current diagnostic and therapeutic approaches.

Lung Cancer Stem Cell Markers as Therapeutic Targets: An Update on Signaling Pathways and Therapies

Cancer stem cells, a relatively small group of self-renewing cancer cells, were first isolated from acute myeloid leukemia. These cells can play a crucial role in tumor metastasis, relapse, and therapy resistance. The cancer stem cell theory may be applied to lung cancer and explain the inefficiency of traditional treatments and eventual recurrence. However, because of the unclear accuracy and illusive biological function of cancer stem cells, some researchers remain cautious about this theory. Despite the ongoing controversy, cancer stem cells are still being investigated, and their biomarkers are being discovered for application in cancer diagnosis, targeted therapy, and prognosis prediction. Potential lung cancer stem cell markers mainly include surface biomarkers such as CD44, CD133, epithelial cell adhesion molecule, and ATP-binding cassette subfamily G member 2, along with intracellular biomarkers such as aldehyde dehydrogenase, sex-determining region Y-box 2, NANOG, and octamer-binding transcription factor 4. These markers have different structures and functions but are closely associated with the stem potential and uncontrollable proliferation of tumor cells. The aberrant activation of major signaling pathways, such as Notch, Hedgehog, and Wnt, may be associated with the expression and regulation of certain lung cancer stem cell markers, thus leading to lung cancer stem cell maintenance, chemotherapy resistance, and cancer promotion. Treatments targeting lung cancer stem cell markers, including antibody drugs, nanoparticle drugs, chimeric antigen receptor T-cell therapy, and other natural or synthetic specific inhibitors, may provide new hope for patients who are resistant to conventional lung cancer therapies. This review provides comprehensive and updated data on lung cancer stem cell markers with regard to their structures, functions, signaling pathways, and promising therapeutic target approaches, aiming to elucidate potential new therapies for lung cancer.

Gli1 promotes epithelial–mesenchymal transition and metastasis of non-small cell lung carcinoma by regulating Snail transcriptional activity and stability

Metastasis is crucial for the mortality of non-small cell lung carcinoma (NSCLC) patients. The epithelial–mesenchymal transition (EMT) plays a critical role in regulating tumor metastasis. Glioma-associated oncogene 1 (Gli1) is aberrantly active in a series of tumor tissues. However, the molecular regulatory relationships between Gli1 and NSCLC metastasis have not yet been identified. Herein, we reported Gli1 promoted NSCLC metastasis. High Gli1 expression was associated with poor survival of NSCLC patients. Ectopic expression of Gli1 in low metastatic A549 and NCI-H460 cells enhanced their migration, invasion abilities and facilitated EMT process, whereas knock-down of Gli1 in high metastatic NCI-H1299 and NCI-H1703 cells showed an opposite effect. Notably, Gli1 overexpression accelerated the lung and liver metastasis of NSCLC in the intravenously injected metastasis model. Further research showed that Gli1 positively regulated Snail expression by binding to its promoter and enhancing its protein stability, thereby facilitating the migration, invasion and EMT of NSCLC. In addition, administration of GANT-61, a Gli1 inhibitor, obviously suppressed the metastasis of NSCLC. Collectively, our study reveals that Gli1 is a critical regulator for NSCLC metastasis and suggests that targeting Gli1 is a prospective therapy strategy for metastatic NSCLC.

The Patient-Derived Cancer Organoids: Promises and Challenges as Platforms for Cancer Discovery

The cancer burden is rapidly increasing in most countries, and thus, new anticancer drugs for effective cancer therapy must be developed. Cancer model systems that recapitulate the biological processes of human cancers are one of the cores of the drug development process. PDCO has emerged as a unique model that preserves the genetic, physiological, and histologic characteristics of original cancer, including inter- and intratumoral heterogeneities. Due to these advantages, the PCDO model is increasingly investigated for anticancer drug screening and efficacy testing, preclinical patient stratification, and precision medicine for selecting the most effective anticancer therapy for patients. Here, we review the prospects and limitations of PDCO compared to the conventional cancer models. With advances in culture success rates, co-culture systems with the tumor microenvironment, organoid-on-a-chip technology, and automation technology, PDCO will become the most promising model to develop anticancer drugs and precision medicine.

Marine Migrastatics: A Comprehensive 2022 Update

Metastasis is responsible for the bad prognosis in cancer patients. Advances in research on metastasis prevention focus attention on the molecular mechanisms underlying cancer cell motility and invasion to improve therapies for long-term survival in cancer patients. The so-called "migrastatics" could help block cancer cell invasion and lead to the rapid development of antimetastatic therapies, improving conventional cancer therapies. In the relentless search for migrastatics, the marine environment represents an important source of natural compounds due to its enormous biodiversity. Thus, this review is a selection of scientific research that has pointed out in a broad spectrum of in vitro and in vivo models the anti-cancer power of marine-derived products against cancer cell migration and invasion over the past five years. Overall, this review might provide a useful up-to-date guide about marine-derived compounds with potential interest for pharmaceutical and scientific research on antimetastatic drug endpoints.

Molecular Mechanisms Involving the Sonic Hedgehog Pathway in Lung Cancer Therapy: Recent Advances

According to the latest statistics from the International Agency for Research on Cancer (IARC), lung cancer is one of the most lethal malignancies in the world, accounting for approximately 18% of all cancer-associated deaths. Yet, even with aggressive interventions for advanced lung cancer, the five-year survival rate remains low, at around 15%. The hedgehog signaling pathway is highly conserved during embryonic development and is involved in tissue homeostasis as well as organ development. However, studies have documented an increasing prevalence of aberrant activation of HH signaling in lung cancer patients, promoting malignant lung cancer progression with poor prognostic outcomes. Inhibitors targeting the HH pathway have been widely used in tumor therapy, however, they still cannot avoid the occurrence of drug resistance. Interestingly, natural products, either alone or in combination with chemotherapy, have greatly improved overall survival outcomes for lung cancer patients by acting on the HH signaling pathway because of its unique and excellent pharmacological properties. In this review, we elucidate on the underlying molecular mechanisms through which the HH pathway promotes malignant biological behaviors in lung cancer, as well as the potential of inhibitors or natural compounds in targeting HH signaling for clinical applications in lung cancer therapy.

Molecular-Genetic Portrait of Breast Cancer with Triple Negative Phenotype

Simple Summary

Breast cancer is a genetically heterogeneous disease with different molecular biological and clinical characteristics. The available knowledge about the genetic heterogeneity of the most aggressive molecular subtype of breast cancer—triple-negative—has led to discoveries in drug treatment. Identification of the molecular-genetic phenotype of breast cancer is an important prognostic factor of the disease and allows personalization of the patient’s treatment.

Abstract

Understanding of the genetic mechanisms and identification of the biological markers of tumor progression that form the individual molecular phenotype of transformed cells can characterize the degree of tumor malignancy, the ability to metastasize, the hormonal sensitivity, and the effectiveness of chemotherapy, etc. Breast cancer (BC) is a genetically heterogeneous disease with different molecular biological and clinical characteristics. The available knowledge about the genetic heterogeneity of the most aggressive molecular subtype of breast cancer—triple-negative (TN)—has led to discoveries in drug treatment, including the use of DNA damaging agents (platinum and PARP inhibitors) for these tumors, as well as the use of immunotherapy. Most importantly, the ability to prescribe optimal drug treatment regimens for patients with TNBC based on knowledge of the molecular-genetic characteristics of this subtype of BC will allow the achievement of high rates of overall and disease-free survival. Thus, identification of the molecular-genetic phenotype of breast cancer is an important prognostic factor of the disease and allows personalization of the patient’s treatment.

Oncogenesis, Microenvironment Modulation and Clinical Potentiality of FAP in Glioblastoma: Lessons Learned from Other Solid Tumors

Currently, glioblastoma (GBM) is the most common malignant tumor of the central nervous system in adults. Fibroblast activation protein (FAP) is a member of the dipeptidyl peptidase family, which has catalytic activity and is engaged in protein recruitment and scaffolds. Recent studies have found that FAP expression in different types of cells within the GBM microenvironment is typically upregulated compared with that in lower grade glioma and is most pronounced in the mesenchymal subtype of GBM. As a marker of cancer-associated fibroblasts (CAFs) with tumorigenic activity, FAP has been proven to promote tumor growth and invasion via hydrolysis of molecules such as brevican in the extracellular matrix and targeting of downstream pathways and substrates, such as fibroblast growth factor 21 (FGF21). In addition, based on its ability to suppress antitumor immunity in GBM and induce temozolomide resistance, FAP may be a potential target for immunotherapy and reversing temozolomide resistance; however, current studies on therapies targeting FAP are still limited. In this review, we summarized recent progress in FAP expression profiling and the understanding of the biological function of FAP in GBM and raised the possibility of FAP as an imaging biomarker and therapeutic target.

Decreased expression of Dlg5 is associated with a poor prognosis and epithelial-mesenchymal transition in squamous cell lung cancer

Background

Discs large homolog 5 (Dlg5) is a newly discovered member of the membrane-associated guanylate kinase superfamily (MAGUK) that is involved in several important processes, including the maintenance of epithelial cell polarity, cell proliferation control, and cell migration and invasion. Decreased expression of Dlg5 has been reported in malignancies arising from different organs. In the present study, we analyzed Dlg5 expression and its prognostic value in squamous cell lung cancer (SqCLC).

Methods

Tumor tissue and adjacent normal tissue sections were collected from 98 patients with SqCLC. The expression levels of Dlg5 and epithelial-mesenchymal transition (EMT) biomarkers in the tissue sections were examined by immunohistochemistry and western blot.

Results

There were 80 males and 18 females in the study cohort. Patients at pathological stages I and IIIA accounted for 64.3% and 35.7% of the cohort, respectively. Western blot showed that Dlg5 expression differed between SqCLC and healthy tissues. Western blot also revealed low Dlg5 expression to be associated with low E-cadherin expression and high vimentin expression, which was consistent with the findings of immunohistochemical staining. Dlg5 expression was significantly correlated with lymph node (LN) metastasis (P=0.001) and disease recurrence (P<0.001), as well as with E-cadherin and vimentin expression (P=0.025 and P=0.001, respectively). Univariate analysis showed that overall survival was significantly correlated with the tumor-node-metastasis (P<0.001) and T (P=0.001) stages, LN metastasis (P<0.001), Dig5 expression (P<0.001), β-catenin expression (P=0.004), and vimentin expression (P=0.002). Patients with overexpression of Dlg5 and β-catenin had a more favorable prognosis than those without. Multivariate analysis revealed that tumor-node-metastasis stage [hazard ratio (HR) =2.124; 95% confidence interval (CI), 1.195–3.777; P=0.010], Dlg5 expression (HR =0.548; 95% CI, 0.313–0.959; P=0.035), β-catenin expression (HR =0.545; 95% CI, 0.312–0.953; P=0.033), and vimentin expression (HR =1.850; 95% CI, 1.050–3.258; P=0.033) could all independently predict the overall survival of patients with SqCLC.

Conclusions

Dlg5 is an important player in EMT which may have potential predictive value for SqCLC prognosis after surgery.

PTCH1 regulates anchorage-independent growth and bone invasion of non-small cell lung cancer cells

Acquisition of metastatic potential by cancer cells is related to cancer stemness and anchorage-independent growth. The onset and progression of cancer are known to involve Hedgehog (HH) signaling that is activated by the binding of HH to the Patched 1 (PTCH1) receptor. However, the functions and mechanisms of action of PTCH1 in the context of bone metastasis remain to be elucidated. In this study, lentivirally-delivered shRNA was used to deplete PTCH1 levels, which resulted in the inhibition of spherical colony formation by the human non-small cell lung cancer (NSCLC) cell line; this suggested that PTCH1 promotes anchorage-independent growth. Concordantly, knockdown of PTCH1 resulted in significantly reduced migration and invasion of NSCLC cells; this was accompanied by the downregulation of MMP7 and SOX2. PTCH1 knockdown resulted in decreased bone destruction and osteoclastogenesis in a mouse bone metastasis model. These results indicate that PTCH1 may be an important regulator of bone invasion, and strongly suggest that knockdown of PTCH1 may decrease the anchorage-independent growth and metastatic potential of NSCLC.

The role of fibroblast activation protein in health and malignancy

Fibroblast activation protein-α (FAP) is a type-II transmembrane serine protease expressed almost exclusively to pathological conditions including fibrosis, arthritis, and cancer. Across most cancer types, elevated FAP is associated with worse clinical outcomes. Despite the clear association between FAP and disease severity, the biological reasons underlying these clinical observations remain unclear. Here we review basic FAP biology and FAP's role in non-oncologic and oncologic disease. We further explore how FAP may worsen clinical outcomes via its effects on extracellular matrix remodeling, intracellular signaling regulation, angiogenesis, epithelial-to-mesenchymal transition, and immunosuppression. Lastly, we discuss the potential to exploit FAP biology to improve clinical outcomes.

HEDGEHOG/GLI Modulates the PRR11-SKA2 Bidirectional Transcription Unit in Lung Squamous Cell Carcinomas

We previously demonstrated that proline-rich protein 11 (PRR11) and spindle and kinetochore associated 2 (SKA2) constituted a head-to-head gene pair driven by a prototypical bidirectional promoter. This gene pair synergistically promoted the development of non-small cell lung cancer. However, the signaling pathways leading to the ectopic expression of this gene pair remains obscure. In the present study, we first analyzed the lung squamous cell carcinoma (LSCC) relevant RNA sequencing data from The Cancer Genome Atlas (TCGA) database using the correlation analysis of gene expression and gene set enrichment analysis (GSEA), which revealed that the PRR11-SKA2 correlated gene list highly resembled the Hedgehog (Hh) pathway activation-related gene set. Subsequently, GLI1/2 inhibitor GANT-61 or GLI1/2-siRNA inhibited the Hh pathway of LSCC cells, concomitantly decreasing the expression levels of PRR11 and SKA2. Furthermore, the mRNA expression profile of LSCC cells treated with GANT-61 was detected using RNA sequencing, displaying 397 differentially expressed genes (203 upregulated genes and 194 downregulated genes). Out of them, one gene set, including BIRC5, NCAPG, CCNB2, and BUB1, was involved in cell division and interacted with both PRR11 and SKA2. These genes were verified as the downregulated genes via RT-PCR and their high expression significantly correlated with the shorter overall survival of LSCC patients. Taken together, our results indicate that GLI1/2 mediates the expression of the PRR11-SKA2-centric gene set that serves as an unfavorable prognostic indicator for LSCC patients, potentializing new combinatorial diagnostic and therapeutic strategies in LSCC.

TMEM107 inhibits EMT and invasion of NSCLC through regulating the Hedgehog pathway

BACKGROUND

Transmembrane protein 107 (TMEM107) is a key regulator of the cilium composition and Hedgehog signaling. Lower TMEM107 gene copies are correlated with poor prognosis in non-small cell lung carcinoma (NSCLC). However, TMEM107 protein expression, localization, and function in NSCLC remain unclear.

METHODS

We first evaluated TMEM107 expression in 12 newly diagnosed cases of NSCLC and paired adjacent healthy tissues by western blotting. We then used an immunohistochemical method to detect TMEM107 expression in 106 paraffin-embedded NSCLC and corresponding normal samples and analyzed its relationship with clinicopathological parameters. Moreover, we determined the impact of TMEM107 upregulation and downregulation on invasion, EMT and Hedgehog pathway in NSCLC cells.

RESULTS

Our results showed that TMEM107 is localized in the cytoplasm and that its expression was lower in NSCLC. TMEM107 expression was positively correlated with cell differentiation and negatively correlated with lymph node metastasis. In A549 and HCC460 cells, downregulation of TMEM107 facilitated cell invasion and upregulated the expression of the Hedgehog pathway target protein Gli1, invasion-associated proteins N-cadherin, vimentin, MMP2, and MMP9, and epithelial-mesenchymal transition (EMT), and inhibited the expression of E-cadherin. Treatment with the Hedgehog pathway inhibitor GANT61 attenuated TMEM107-knockdown-induced EMT and invasiveness.

CONCLUSIONS

These results indicate that TMEM107 inhibits EMT and invasion by negatively regulating Hedgehog signaling and that it is downregulated in NSCLC.

KEY POINTS

TMEM107 expression is lower in NSCLC tissues and correlates with poor prognosis TMEM107 inhibits invasion of NSCLC cells TMEM107 inhibits EMT of NSCLC cells Downregulation of TMEM107 activates the Hedgehog signaling pathway Downregulation of TMEM107 promotes EMT and migration in NSCLC by activating the Hedgehog signaling pathway.

Collagen I Induces Preeclampsia-Like Symptoms by Suppressing Proliferation and Invasion of Trophoblasts

Preeclampsia is a common obstetric disorder affecting 2-8% of pregnancy worldwide. Fibrosis is an important histological change occurring in preeclamptic placenta, and might depend on the excess deposition of collagen I. However, the role of fibrotic placenta and collagen I in the pathogenesis of preeclampsia remains unclear. Therefore, we analyzed the collagen deposition and the expression of Collagen I in human placenta by Masson staining, Sirius red staining and western blotting. Further, the role of collagen I in preeclampsia pathogenesis was studied in C57BL/6 mice. HTR-8/SVneo cells were used to investigate the mechanisms underlying the effects of collagen I in trophoblasts by transcriptome sequencing and pharmacological agonists. Human preeclamptic placenta exhibited a significantly higher degree of fibrosis in stem villi and terminal villi than normal placenta, and was characterized by collagen I deposition. In vivo, a single injection of collagen I on gestational day 0.5 led to an increase in systolic pressure of pregnant mice from gestational days 4.5-17.5, to a decrease in weight and number of embryos, and to enhanced placental collagen I expression and degree of fibrosis compared with control mice. In vitro, collagen I attenuated the proliferation and invasion of HTR-8SV/neo cells. This effect could be reversed by treatment with agonists of ERK and β-catenin. Moreover, transcriptome sequencing demonstrated that signaling pathways related to cell proliferation and invasion were significantly downregulated in HTR-8SV/neo cells. Thus, we propose that collagen I induced preeclampsia-like symptoms by suppressing the proliferation and invasion of trophoblasts through inhibition of the ERK phosphorylation and WNT/β-catenin signaling pathways. Our findings could pave the way to the discovery of small-molecule inhibitors for preeclampsia treatment and future studies with larger sample size are required.

Atmospheric fine particulate matter and epithelial mesenchymal transition in pulmonary cells: state of the art and critical review of the in vitro studies

Exposure to fine particulate matter (PM_2.5) has been associated with several diseases including asthma, chronic obstructive pulmonary disease (COPD) and lung cancer. Mechanisms such as oxidative stress and inflammation are well-documented and are considered as the starting point of some of the pathological responses. However, a number of studies also focused on epithelial-mesenchymal transition (EMT), which is a biological process involved in fibrotic diseases and cancer progression notably via metastasis induction. Up until now, EMT was widely reported in vivo and in vitro in various cell types but investigations dealing with in vitro studies of PM_2.5 induced EMT in pulmonary cells are limited. Further, few investigations combined the necessary endpoints for validation of the EMT state in cells: such as expression of several surface, cytoskeleton or extracellular matrix biomarkers and activation of transcription markers and epigenetic factors. Studies explored various cell types, cultured under differing conditions and exposed for various durations to different doses. Such unharmonized protocols (1) might introduce bias, (2) make difficult comparison of results and (3) preclude reaching a definitive conclusion regarding the ability of airborne PM_2.5 to induce EMT in pulmonary cells. Some questions remain, in particular the specific PM_2.5 components responsible for EMT triggering. The aim of this review is to examine the available PM_2.5 induced EMT in vitro studies on pulmonary cells with special emphasis on the critical parameters considered to carry out future research in this field. This clarification appears necessary for production of reliable and comparable results.

Immunodetection of Epithelial-Mesenchymal Transition and Tumor Proliferation Markers in GLi-1-positive Oral Squamous Cell Carcinoma

In oral squamous cell carcinoma (OSCC), involvement and activation of the Hedgehog pathway (HH) may be related to epithelial-mesenchymal transition and cell proliferation. The present study aimed to evaluate epithelial-mesenchymal transition and proliferative potential in OSCC cases demonstrating activation of the HH pathway. Twenty-three GLi-1-positive OSCC cases were submitted to immunohistochemical detection of Snail, Slug, N-cadherin, E-cadherin, β-catenin, and MCM3 proteins. Clinical-pathologic immunoexpression data were obtained from the invasion front and tumor islets, and then compared. At the invasion front, OSCC cases presented positive Snail, Slug, and MCM3 expression in the nuclei of tumor cells. Loss of membrane and cytoplasmic expression of E-cadherin and β-catenin was also observed. Positive N-cadherin expression was observed in 31.78% of the cases. GLi-1 immunoexpression was associated with loss of membrane E-cadherin (P<0.001), membrane β-catenin (P<0.001), and cytoplasmic β-catenin (P=0.02) expression. In the tumor islets, we observed nuclear expression of GLi-1, Snail, Slug, and MCM3. E-cadherin and β-catenin showed positivity in tumor cell membranes. Statistically significant positive correlations between GLi-1 and Snail (P=0.05), E-cadherin (P=0.01), and cytoplasmic β-catenin (P=0.04) were found. GLi-1 was associated with clinical staging, while membrane β-catenin expression was related to the presence of metastasis in lymph nodes and to clinical staging. The HH pathway may be involved in regulating the expression of the mesenchymal phenotype. The loss of membrane E-cadherin and β-catenin expression was observed at the tumor front region, whereas cell adhesion protein expression was detected in tumor islets regardless of MCM3.

Sonic Hedgehog Regulates Proliferation, Migration and Invasion of Synoviocytes in Rheumatoid Arthritis via JNK Signaling

Activated fibroblast-like synoviocytes (FLSs) play a central role in the formation of synovial pannus and joint destruction in rheumatoid arthritis (RA). Targeting FLSs could be a potential therapeutic strategy. The objective of this study is to explore the role of c-Jun N-terminal kinase (JNK) in proliferation, migration and invasion of FLSs promoted by the sonic hedeghog (SHH) signaling pathway in patients with RA. Activation of SHH signaling was evaluated by real-time PCR and Western Blot. Levels of phosphorylation of JNK and c-Jun were detected by Western Blot. FLSs proliferation was quantified by Cell Counting Kit-8 (CCK-8) assay and flow cytometry. Cell migration and invasion were assessed by wound healing assay and Transwell chamber assay. Invasiveness of FLSs in vivo was evaluated using a humanized synovitis animal model. We observed that treatment of SHH agonist (SAG) significantly increased the levels of phosphorylation of JNK and c-Jun, while SHH antagonist (cyclopamine) significantly decreased the expression of phospho-JNK and phospho-c-Jun in FLSs. The elevated level of phospho-c-Jun stimulated by SAG was decreased in the presence of JNK inhibitor (SP600125) (P < 0.001). FLSs proliferation, migration and invasion were promoted by SHH agonist (P < 0.05). However, the enhanced aggressiveness of FLSs was abolished in the presence of JNK inhibitor (P < 0.05). In vivo study showed that the invasion of FLSs into cartilage was increased by SHH overexpression and the excessive invasiveness was inhibited by blockade of JNK signaling (P < 0.01). These results suggest that JNK is one of the downstream molecules mediating the effect of SHH signaling in FLSs. These findings indicate that SHH-JNK signaling could be a potential therapeutic target to suppress the aggressiveness of FLSs and prevent articular damage of RA.

Glioma-associated oncogene homolog 1 stimulates FOXP3 to promote non-small cell lung cancer stemness

Glioma-associated oncogene homolog 1 (GLI1), an oncogenic molecule in non-small cell lung cancer (NSCLC), promotes the growth of NSCLC by enhancing lung cancer stem cells (LCSCs). However, the mechanism responsible remains unknown. FOXP3 is known to maintain LCSCs. The aim of this study was to explore whether GLI1 enhanced LCSCs via stimulating FOXP3. Experiments were performed in NSCLC tissue samples, cell lines and the animal tumor model. The expression of GLI1- and LCSC-related molecules was assessed at protein and mRNA levels. Relevant cell functions were also determined. A tumor xenograft mouse model was established to confirm the oncogenic role of GLI1. We confirmed that the expression of GLI1 was up-regulated in the tumor tissues of NSCLC compared with adjacent non-tumor tissues. But no significant association between GLI1 and clinicopathological characteristics was found. GLI1 expression was positively correlated with FOXP3 and it could promote FOXP3 expression likely via acting on the promoter of FOXP3. Along with the upregulation of FOXP3, GLI1 increased the expression of LCSC markers, ALDH1A1 and OCT4A, and the formation of tumor spheres, whereas the inhibition of GLI1 decreased the above features. We also found the involvement of Notch1 activation in GLI1-mediated FOXP3 pathway. The In vivo mouse tumor model verified the positive role of GLI1 in the growth of the tumor. Collectively, this study has demonstrated that GLI1 stimulates FOXP3 to promote LCSCs.

Sonic Hedgehog/Gli1 Signaling Pathway Regulates Cell Migration and Invasion via Induction of Epithelial-to-mesenchymal Transition in Gastric Cancer

Background: The aberrant activation of the Sonic hedgehog (Shh) signaling pathway is involved in progression of several types of cancer, including gastric cancer (GC). However, it remains uncertain whether it also plays a critical role in promoting cancer initiation and progression by inducing epithelial-to-mesenchymal transition (EMT) in GC. Thus, the aim of the present study was to determine whether the Shh pathway is involved in GC, and to investigate the function of the Shh pathway in the induction of EMT in GC. Materials and methods: The expression levels of Shh pathway members and EMT markers were examined in GC tissues by immunohistochemistry. The association between these factors and patient clinicopathological characteristics was analyzed. In addition, Gli-antagonist 61 (GANT61) was used to block Shh/Gli1 pathway activity, and recombinant Shh proteins (N-Shh) were used to activate the Shh pathway in GC cells. Wound healing and Transwell invasion and migration assays were performed to assess the effects of the Shh pathway on the migration and invasion of GC cells in vitro. Furthermore, western blot analysis was used to examine the changes in protein expression. Results: The results demonstrated that these Shh/Gli1 pathway members were upregulated in GC tissues, and that Gli1 upregulation was associated with tumor progression and a poor prognosis. Gli1 expression was negatively associated with E-cadherin (E-Cad) expression, and positively with Vimentin (VIM) expression in GC specimens. Further analysis revealed that when the Shh/Gli1 pathway was activated, the migratory and invasive abilities of GC cells were enhanced, and the expression levels of Gli1 and VIM were increased, while E-Cad expression was decreased. Opposite results were observed when the Shh/Gli1 pathway was blocked by GANT61. Conclusions: The present study indicated that the Shh/Gli1 pathway exhibits an abnormal activation pattern in GC with possible predictive and prognostic significance. The Shh/Gli1 pathway may promote the migratory and invasive potential of GC cells by inducing EMT. The Shh/Gli1 pathway can thus be considered as a potential therapeutic target for GC.

Targeting the Hedgehog pathway in combination with X‑ray or carbon ion radiation decreases migration of MCF‑7 breast cancer cells

The use of carbon ion therapy for cancer treatment is becoming more widespread due to the advantages of carbon ions compared with X‑rays. Breast cancer patients may benefit from these advantages, as the surrounding healthy tissues receive a lower dose, and the increased biological effectiveness of carbon ions can better control radioresistant cancer cells. Accumulating evidence indicates that the Hedgehog (Hh) pathway is linked to the development and progression of breast cancer, as well as to resistance to X‑irradiation and the migratory capacity of cancer cells. Hence, there is an increasing interest in targeting the Hh pathway in combination with radiotherapy. Several studies have already investigated this treatment strategy with conventional radiotherapy. However, to the best of our knowledge, the combination of Hh inhibitors with particle therapy has not yet been explored. The aim of the present study was to investigate the potential of the Hh inhibitor GANT61 as an effective modulator of radiosensitivity and migration potential in MCF‑7 breast cancer cells, and compare potential differences between carbon ion irradiation and X‑ray exposure. Although Hh targeting was not able to radiosensitise cells to any radiation type used, the combination of GANT61 with X‑rays or carbon ions (energy: 95 MeV/n; linear energy transfer: 73 keV/µm) was more effective in decreasing MCF‑7 cell migration compared with either radiation type alone. Gene expression of the Hh pathway was affected to different degrees in response to X‑ray and carbon ion irradiation, as well as in response to the combination of GANT61 with irradiation. In conclusion, combining Hh inhibition with radiation (X‑rays or carbon ions) more effectively decreased breast cancer cell migration compared with radiation treatment alone.

House dust mite induces Sonic hedgehog signaling that mediates epithelial‑mesenchymal transition in human bronchial epithelial cells

Epithelial‑mesenchymal transition (EMT) provides a valuable source of fibroblasts that produce extracellular matrix in airway walls. The Sonic hedgehog (SHH) signaling pathway plays an essential role in regulating tissue turnover and homeostasis. SHH is strikingly upregulated in the bronchial epithelia during asthma. Snail1 is a major target of SHH signaling, which regulates EMT and fibroblast motility. The present study was designed to ascertain whether the combination of house dust mite (HDM) and transforming growth factor β1 (TGF‑β1) could induce EMT via the SHH signaling pathway in human bronchial epithelial cells (HBECs). HBEC cultures were treated with HDM/TGF‑β1 for different periods of time. The involvement of SHH signaling and EMT biomarkers was evaluated by quantitative real‑time PCR, western blotting and immunofluorescence staining. Small‑interfering RNA (siRNA) for glioma‑associated antigen‑1 (Gli1) or cyclopamine was used to inhibit SHH signaling in HBECs. HBECs stimulated by HDM/TGF‑β1 exhibited morphological features of EMT. E‑cadherin (an epithelial marker) was decreased after a 72‑h exposure to HDM/TGF‑β1 compared to that in the control cells, and the expression of type I collagen and FSP1 (mesenchymal markers) was increased. HDM/TGF‑β1 activated the SHH signaling pathway in HBECs, which led to Gli1 nuclear translocation and the transcriptional activation of Snail1 expression. Moreover, gene silencing or the pharmacological inhibition of Gli1 ameliorated EMT. In summary, these findings suggest that HDM/TGF‑β1 may induce EMT in HBECs via an SHH signaling mechanism. Inhibition of SHH signaling may be a novel therapeutic method for preventing airway remodeling in asthma.

Saikosaponin-d Inhibits the Hepatoma Cells and Enhances Chemosensitivity Through SENP5-Dependent Inhibition of Gli1 SUMOylation Under Hypoxia

Chemosensitivity is one of the key factors affecting the therapeutic effect on cancer, but the clinical application of corresponding drugs is rare. Hypoxia, a common feature of many solid tumors, including hepatocellular carcinoma (HCC), has been associated with resistance to chemotherapy in part through the activation of the Sonic Hedgehog (SHh) pathway. Hypoxia has also been associated with the increased SUMOylation of multiple proteins, including GLI family proteins, which are key mediators of SHh signaling, and has become a promising target to develop drug-resistant drugs for cancer treatment. However, there are few target drugs to abrogate chemotherapy resistance. Saikosaponin-d (Ssd), one of the main bioactive components of Radix bupleuri, has been reported to exert multiple biological effects, including anticancer activity. Here, we first found that Ssd inhibits the malignant phenotype of HCC cells while increasing their sensitivity to the herpes simplex virus thymidine kinase/ganciclovir (HSVtk/GCV) drug system under hypoxia in vitro and in vivo. Furthermore, we had explored that GLI family activation and extensive protein SUMOylation were characteristics of HCC cells, and hypoxia could activate the SHh pathway and promote epithelial-mesenchymal transition (EMT), invasion, and chemosensitivity in HCC cells. SUMOylation is required for hypoxia-dependent activation of GLI proteins. Finally, we found that Ssd could reverse the effects promoted by hypoxia, specifically active sentrin/small ubiquitin-like modifier (SUMO)-specific protease 5 (SENP5), a SUMO-specific protease, in a time- and dose-dependent manner while inhibiting the expression of SUMO1 and GLI proteins. Together, these findings confirm the important role of Ssd in the chemoresistance of liver cancer, provide some data support for further understanding the molecular mechanisms of Ssd inhibition of malignant transformation of HCC cells, and provide a new perspective for the application of traditional Chinese medicine in the chemical resistance of liver cancer.

Identification of α-N-catenin as a novel tumor suppressor in neuroblastoma

The lost expression of α-catenin has been found in cancers, and reinstalling α-catenin inhibits tumor growth. Here we hypothesized that the α-N-catenin, a homologous member of α-catenin and neural-specific expressed, functions as a novel tumor suppressor in neural crest-derived tumor, neuroblastoma. We correlated CTNNA2 (encodes α-N-catenin) expression to neuroblastoma disease relapse-free survival probability using publicly accessible human neuroblastoma datasets in R2 platform. The result showed that it negatively correlated to relapse-free survival probability significantly in patients with neuroblastoma with non-MYCN amplified tumor. Conversely, overexpressing CTNNA2 suppressed the neuroblastoma cell proliferation as measuring by the clonogenesis, inhibited anchorage-independent growth with soft agar colony formation assay. Forced expression of CTNNA2 decreased cell migration and invasion. Further, overexpression of CTNNA2 reduced the secretion of angiogenic factor IL-8 and HUVEC tubule formation. Our results show, for the first time, that α-N-catenin is a tumor suppressor in neuroblastoma cells. These findings were further corroborated with in vivo tumor xenograft study, in which α-N-catenin inhibited tumor growth and reduced tumor blood vessel formation. Interestingly, this is only observed in SK-N-AS xenografts lacking MYCN expression, and not in BE(2)-C xenografts with MYCN amplification. Mechanistically, α-N-catenin attenuated NF-κB responsive genes by inhibiting NF-κB transcriptional activity. In conclusion, these data demonstrate that α-N-catenin is a tumor suppressor in non-MYCN-amplified neuroblastomas and it inhibits NF-κB signaling pathway to suppress tumor growth in human neuroblastomas. Therefore, restoring the expression of α-N-catenin can be a novel therapeutic approach for neuroblastoma patients who have the deletion of CTNNA2 and lack of MYCN amplification.

The Combination of Particle Irradiation With the Hedgehog Inhibitor GANT61 Differently Modulates the Radiosensitivity and Migration of Cancer Cells Compared to X-Ray Irradiation

Due to the advantages of charged particles compared to conventional radiotherapy, a vast increase is noted in the use of particle therapy in the clinic. These advantages include an improved dose deposition and increased biological effectiveness. Metastasis is still an important cause of mortality in cancer patients and evidence has shown that conventional radiotherapy can increase the formation of metastasizing cells. An important pathway involved in the process of metastasis is the Hedgehog (Hh) signaling pathway. Recent studies have demonstrated that activation of the Hh pathway, in response to X-rays, can lead to radioresistance and increased migratory, and invasive capabilities of cancer cells. Here, we investigated the effect of X-rays, protons, and carbon ions on cell survival, migration, and Hh pathway gene expression in prostate cancer (PC3) and medulloblastoma (DAOY) cell lines. In addition, the potential modulation of cell survival and migration by the Hh pathway inhibitor GANT61 was investigated. We found that in both cell lines, carbon ions were more effective in decreasing cell survival and migration as well as inducing more significant alterations in the Hh pathway genes compared to X-rays or protons. In addition, we show here for the first time that the Hh inhibitor GANT61 is able to sensitize DAOY medulloblastoma cells to particle radiation (proton and carbon ion) but not to conventional X-rays. This important finding demonstrates that the results of combination treatment strategies with X-ray radiotherapy cannot be automatically extrapolated to particle therapy and should be investigated separately. In conclusion, combining GANT61 with particle radiation could offer a benefit for specific cancer types with regard to cancer cell survival.

Role of Hedgehog Signaling in Breast Cancer: Pathogenesis and Therapeutics

Breast cancer (BC) is the leading cause of cancer-related mortality in women, only followed by lung cancer. Given the importance of BC in public health, it is essential to identify biomarkers to predict prognosis, predetermine drug resistance and provide treatment guidelines that include personalized targeted therapies. The Hedgehog (Hh) signaling pathway plays an essential role in embryonic development, tissue regeneration, and stem cell renewal. Several lines of evidence endorse the important role of canonical and non-canonical Hh signaling in BC. In this comprehensive review we discuss the role of Hh signaling in breast development and homeostasis and its contribution to tumorigenesis and progression of different subtypes of BC. We also examine the efficacy of agents targeting different components of the Hh pathway both in preclinical models and in clinical trials. The contribution of the Hh pathway in BC tumorigenesis and progression, its prognostic role, and its value as a therapeutic target vary according to the molecular, clinical, and histopathological characteristics of the BC patients. The evidence presented here highlights the relevance of the Hh signaling in BC, and suggest that this pathway is key for BC progression and metastasis.

Retinoids induce antagonism between FOXO3A and FOXM1 transcription factors in human oral squamous cell carcinoma (OSCC) cells

To gain a greater understanding of oral squamous cell carcinoma (OSCC) we investigated the actions of all-trans-retinoic acid (RA; a retinoid), bexarotene (a pan-RXR agonist), and forkhead box (FOX) transcription factors in human OSCC-derived cell lines. RA and bexarotene have been shown to limit several oncogenic pathways in many cell types. FOXO proteins typically are associated with tumor suppressive activities, whereas FOXM1 acts as an oncogene when overexpressed in several cancers. RA and/or bexarotene increased the transcript levels of FOXO1, FOXO3A, and TRAIL receptors; reduced the transcript levels of FOXM1, Aurora kinase B (AURKB), and vascular endothelial growth factor A (VEGFA); and decreased the proliferation of OSCC-derived cell lines. Also, RA and/or bexarotene influenced the recruitment of FOXO3A and FOXM1 to target genes. Additionally, FOXM1 depletion reduced cell proliferation, decreased transcript levels of downstream targets of FOXM1, and increased transcript levels of TRAIL receptors. Overexpression of FOXO3A decreased proliferation and increased binding of histone deacetylases (HDACs) 1 and 2 at the FOXM1, AURKB, and VEGFA promoters. This research suggests novel influences of the drugs RA and bexarotene on the expression of FOXM1 and FOXO3A in transcriptional regulatory pathways of human OSCC.

Triptonide inhibits lung cancer cell tumorigenicity by selectively attenuating the Shh-Gli1 signaling pathway

Lung cancer is a leading lethal disease with a 5-year survival rate of only 16%. Inadequate potent anti-cancer drugs appear to be a bottleneck in the treatment of lung cancer; hence, how to develop effective anti-lung cancer therapeutics is an urgent problem. In this study, we aim to explore a novel compound with potent anti-lung cancer effect and study its anti-cancer mechanisms. We found that triptonide at very low concentrations of 5-10 nM caused a marked suppression of cell proliferation and colony formation of lung cancer cells. More interestingly, triptonide also robustly inhibited the lung cancer cell formation of tumor spheres, and reduced the stemness and tumorigenicity of the sphere-forming cells. In vivo studies showed that administration of triptonide significantly inhibited the tumor growth with low toxicity. Molecular mechanistic studies revealed that triptonide significantly decreased expression of the Gli1 at both mRNA and protein levels by repressing Gli1 gene promoter activity. Additionally, triptonide reduced the levels of cancer stem cell key signaling protein sonic hedgehog (Shh), but increased the amount of Ptch1, a protein binding to SMO to diminish the Shh signal transduction, thus inhibition of the Shh-Gli1 signaling pathway. Together, our findings show that triptonide effectively inhibits lung cancer cell growth, stemness, and tumorigenicity, and support the notion that triptonide is a new Shh-Gli1 signaling inhibitor and a novel anti-lung cancer drug candidate for further developing effective lung cancer therapeutics.

Hedgehog Signaling in Lung Cancer: From Oncogenesis to Cancer Treatment Resistance

Hedgehog signaling pathway is physiologically activated during embryogenesis, especially in lung development. It is also reactivated in many solid tumors. In lung cancer, Hedgehog pathway is closely associated with cancer stem cells (CSCs). Recent works have shown that CSCs produced a full-length Sonic Hedgehog (Shh) protein, with paracrine activity and induction of tumor development. Hedgehog pathway is also involved in tumor drug resistance in lung cancer, as cytotoxic chemotherapy, radiotherapy, and targeted therapies. This review proposes to describe the activation mechanisms of Hedgehog pathway in lung cancer, the clinical implications for overcoming drug resistance, and the perspectives for further research.

Gli promotes epithelial-mesenchymal transition in human lung adenocarcinomas

Adenocarcinoma is the most common type of lung cancer. Epithelial-mesenchymal transition (EMT) is required for tumor invasion/metastasis and the components that control this process are potential therapeutic targets. This study we examined the role of Gli in lung adenocarcinoma and whether its activation regulates metastasis through EMT in lung adenocarcinoma. We found that tumors with high Gli expression had significantly lower E-Cadherin expression in two independent cohorts of patients with lung adenocarcinoma that we studied. In vitro up-regulation of SHh resulted in increased cell migration while small molecule inhibitors of Smo or Gli significantly reduced cell mobility both in a wound healing assay and in a 3D cell invasion assay. Inhibition of Gli in vivo decreased tumor growth and induced an increase in E-Cadherin expression. Our results indicate that Gli may be critical for lung adenocarcinoma metastasis and that a novel Gli inhibitor shows promise as a therapeutic agent by preventing cell migration and invasion in vitro and significantly reducing tumor growth and increasing E-Cadherin expression in vivo.

Old Sonic Hedgehog, new tricks: a new paradigm in thoracic malignancies

The Sonic Hedgehog (Shh) pathway is physiologically involved during embryogenesis, but is also activated in several diseases, including solid cancers. Previous studies have demonstrated that the Shh pathway is involved in oncogenesis, tumor progression and chemoresistance in lung cancer and mesothelioma. The Shh pathway is also closely associated with epithelial-mesenchymal transition and cancer stem cells. Recent findings have revealed that a small proportion of lung cancer cells expressed an abnormal full-length Shh protein, associated with cancer stem cell features. In this paper, we review the role of the Shh pathway in thoracic cancers (small cell lung cancer, non-small cell lung cancer, and mesothelioma) and discuss the new perspectives of cancer research highlighted by the recent data of the literature.

Casticin inhibits the epithelial-mesenchymal transition in ovarian carcinoma via the hedgehog signaling pathway

Casticin inhibits migration, invasion and induced apoptosis in numerous cancer cells; however, the Hedgehog (Hh) signaling pathway is a key factor in the epithelial-mesenchymal transition (EMT). The present study aimed to assess whether casticin affects the expression of members of the Hh signaling pathway and EMT effectors in ovarian carcinoma. The ovarian cancer SKOV3 cell line was incubated in the presence of various concentrations of casticin or cyclopamine. Next, the expression levels of the main Hh signaling effector glioma-associated oncogene-1 (Gli-1) and EMT-associated factors [Twist-related protein 1 (Twist1), E-cadherin and N-cadherin] were determined by western blotting and reverse transcription-quantitative polymerase chain reaction. Cell proliferation and growth were assessed using MTT and soft agar assays; cell migration and invasion was evaluated using an in vitro migration assay and a transwell invasion assay, respectively. Compared with control group values, Gli-1, Twist1 and N-cadherin expression levels were reduced, whereas E-cadherin levels were increased in the casticin- and cyclopamine-treated groups. Incubation with casticin or cyclopamine resulted in markedly reduced SKOV3 cell viability, migration and invasion, in a dose-dependent manner. To the best of our knowledge, the findings of the present study indicated for first time that casticin may inhibit EMT via Hh signaling in vitro, reducing the migratory ability of ovarian cancer cells.

Claudin-3 Inhibits Lung Squamous Cell Carcinoma Cell Epithelial-mesenchymal Transition and Invasion via Suppression of the Wnt/β-catenin Signaling Pathway

Altered expression of claudin-3 (CLDN3), a key cytoskeletal structural protein of the tight junctions in the epithelium, is associated with the development and metastasis of various human cancers. CLDN3 expression has been shown to be significantly associated with the prognosis of lung squamous cell carcinoma (SqCC). This study investigated the role of CLDN3 in inhibiting lung SqCC cell migration and invasion as well as the underlying molecular mechanisms. The CLDN3 levels were assessed between 20 paired lung SqCC tissues and adjacent normal tissues using quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. The ectopic CLDN3 overexpression or knockdown was generated by using a plasmid carrying CLDN3 cDNA or shRNA, respectively. CLDN3 expression was significantly reduced in lung SqCC tissues vs. the adjacent normal tissues. The ectopic CLDN3 overexpression markedly inhibited the migration, invasion, and epithelial-mesenchymal transition (EMT) of lung cancer H520 cells, whereas CLDN3 knockdown had an inverse effect on SK-MES-1 cells. However, cell viability and plate colony formation assays showed that both CLDN3 knockdown and overexpression did not affect SqCC cell proliferation. Both tissue and cell data revealed that CLDN3 expression was significantly associated with the expression of the EMT biomarkers E-cadherin and Vimentin. Furthermore, CLDN3-modulated EMT and expression of the EMT markers were through regulation of the Wnt/β-catenin signaling pathway. In conclusion, this study identified reduced CLDN3 expression in lung SqCC tissues, which was associated with the progression and metastasis of lung SqCC and was attributed to EMT by activation of the Wnt pathway. Thus, CLDN3 could be further evaluated as a novel biomarker for predicting the prognosis of lung SqCC and as a target for the treatment of lung SqCC in the future.

FGFR1 promotes the stem cell-like phenotype of FGFR1-amplified non-small cell lung cancer cells through the Hedgehog pathway

Cancer stem cell-like phenotype is critical for tumor formation and treatment resistance. FGFR1 is found to be amplified in non-small cell lung cancer, particularly in the lung squamous cell cancer (LSCC). Whether FGFR1 contributes to the maintenance of stem cell-like phenotype of FGFR1-amplified lung cancer cells remains elusive. In this study, treatment with FGFR1 inhibitor AZD4547 suppressed the growth of tumor spheres and reduced ALDH positive proportion in FGFR1-amplified lung cancer cells in vitro, as well as inhibited the growth of oncospheres and parental cells in xenograft models. Knockdown of FGFR1 recaptured the similar effect as AZD4547 in vitro. Furthermore, activation of FGFR1 and subsequently its downstream ERK signaling enhanced the expression and transcriptional activity of GLI2, which could be blocked by FGFR1 inhibitor/silencing or ERK inhibitor. Knockdown of GLI2 directly inhibited the stem-like phenotype of FGFR1-amilified cells, whereas overexpression of GLI2 sufficiently rescued the phenotype caused by FGFR1 knockdown. Notably we also identified a correlation between FGFR1 and GLI2 expressions from clinical data, as well as an inverse relationship with progression free survival (PFS). Together our study suggests that the FGFR1/GLI2 axis promotes the lung cancer stem cell-like phenotype. These results support a rational strategy of combination of FGFR1 and GLI inhibitors for treatment of FGFR1-amplified lung cancers, especially LSCC.

Gli is activated and promotes epithelial-mesenchymal transition in human esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) accounts for the most esophageal cancer cases in the US, and is notoriously aggressive. This study examines the role of Sonic Hedgehog (SHh)/Gli signaling in the regulation of epithelial-mesenchymal transition (EMT), a process tied to invasion and metastasis, in EAC. Gli/EMT protein expression levels were examined by western blot in paired EAC patient tissues (n = 24) and cell lines (OE19, OE33). Functional analyses were performed (siRNA, treatment with Gli-inhibitor, AKT-inhibitor, and N-Shh recombinant proteins) to investigate SHh/Gli signaling and EMT, cell cycle, and prognostic markers in EAC cell lines. MTS, luciferase reporter, qRT-PCR, western blot, wound healing, and transwell assays were executed to analyze pathway activity, cell migration, and invasion. Aberrant Gli1/2 expression was found in EAC patient tissues, and was significantly associated with increased EMT and AKT pathway activity. Stimulation of SHh/Gli resulted in EMT signaling, including expression of E-cadherin, N-cadherin, Vimentin, β-catenin, Snail, and Slug, as well as cell cycle progression at mRNA and protein levels in EAC cell lines. Gli inhibition via small molecule administration and siRNA significantly reduced EMT, decreasing cell mobility and invasion. Both Gli and AKT inhibition rescued E-cadherin expression and suppressed AKT phosphorylation. This study provides evidence for a strong association between aberrant Gli1/2 expression and AKT/EMT markers in EAC; activated SHh/Gli signaling may be a critical component in promoting cell survival, metastases, and resistance to chemotherapy, and represents a promising avenue to target tumor proliferation and mobility.

Fibroblast activation protein-α promotes the growth and migration of lung cancer cells via the PI3K and sonic hedgehog pathways

A characteristic of the epithelial-to-mesenchymal transition in cancer cells is the upregulation of mesenchymal markers. Fibroblast activation protein α (FAPα) is predominantly expressed by stromal fibroblasts. Previous studies have demonstrated that FAPα is also expressed by certain epithelium-derived cancer cells and is involved in the regulation of certain signaling pathways. One of our previous studies showed that FAPα promoted the proliferation of breast cancer cells via the phosphatidylinositol-3-kinase (PI3K) signaling pathway. In the present study, the A549 adenocarcinoma (AC) and SK-MES-1 squamous cell carcinoma (SCC) lung cancer cell lines were transfected with FAPα. The FAPα-expressing SK-MES-1 cells exhibited an increased growth rate, whereas the FAPα-expressing A549 cells exhibited a similar growth rate, compared with respective empty vector-transfected control cells. Electric cell-substrate impedance sensing (ECIS)-based attachment and wound-healing assays showed that the overexpression of FAPα markedly increased the adhesive and migratory properties of the SK-MES-1 cells but not those of the A549 cells. Additionally, inhibitors of focal adhesion kinase, agonist-induced phospholipase C, neural Wiskott-Aldrich syndrome protein, extracellular signal-regulated kinase, Rho-associated protein kinase, PI3K, and sonic hedgehog (SHH) were used to evaluate the interaction between FAPα and signaling pathways. Only the inhibitors of SHH and PI3K inhibited the increased motility of the FAPα-expressing SK-MES-1 cells. Western blot analysis confirmed the activation of PI3K/AKT and SHH/GLI family zinc finger 1 signaling in the FAPα-expressing SK-MES-1 cells. These results revealed that FAPα promoted the growth, adhesion and migration of lung SCC cells. In addition, FAPα regulated lung cancer cell function, potentially via the PI3K and SHH pathways. Further investigations are required to examine the role of FAPα in lung AC cells.

Down-regulation of microRNA-224 -inhibites growth and epithelial-to-mesenchymal transition phenotype -via modulating SUFU expression in bladder cancer cells

Aberrant expression of miR-224 is usually found in cancer studies; however, the role of miR-224 has seldom been reported in bladder cancer (BC). We explored miR-224's function and the underlying mechanism in BC. It was found that miR-224 expression was significantly up-regulated in BC tissues and cell lines. Knockdown of miR-224 decreased BC cell growth and invasion both in vitro and in vivo. We identified the SUFU protein as a downstream target of miR-224 by using luciferase and western blot assays. We proposed that miR-224 promoted BC cell growth and invasion via sustaining the activity of Hedgehog pathway, which was negatively regulated by SUFU. Taken together, our study demonstrated that miR-224 may function as an onco-miR in BC and suggested that miR-224 may be a potential therapeutic target for BC patients.

Oncogenic function of TUSC3 in non-small cell lung cancer is associated with Hedgehog signalling pathway

Non-small cell lung cancer (NSCLC) represents 75-80% of all lung carcinomas, which is the most common cause of death from cancer. Tumour suppressor candidate 3 (TUSC3) is pivotal in many biochemical functions and cytological processes. Dis-regulation of TUSC3 is frequently observed in epithelial cancers. In this study, we observed up-regulated TUSC3 expression at the mRNA and protein levels in clinical NSCLC samples compared with adjacent non-tumorous lung tissues. The expression level of TUSC3 is significantly correlated with tumour metastasis and patient survival. Overexpression of TUSC3 in NSCLC cells led to increased proliferation, migration, and invasion in vitro and accelerated xenograft tumour growth in vivo, while the opposite effects were achieved in TUSC3-silenced cells. Increased GLI1, SMO, PTCH1, and PTCH2 abundance were observed in TUSC3 overexpressed cells using western blotting. Co-immunoprecipitation and immunofluorescence analyses further revealed interaction between TUSC3 and GLI1. In conclusion, our study demonstrated an oncogenic role of TUSC3 in NSCLC and showed that dis-regulation of TUSC3 may affect tumour cell invasion and migration through possible involvement in the Hedgehog (Hh) signalling pathway.

The mechanism of epithelial-mesenchymal transition induced by TGF-β1 in neuroblastoma cells

Neuroblastoma is the second most common extracranial malignant solid tumor that occurs in childhood, and metastasis is one of the major causes of death in neuroblastoma patients. The epithelial-mesenchymal transition (EMT) is an important mechanism for both the initiation of tumor invasion and subsequent metastasis. Therefore, this study investigated the mechanism by which transforming growth factor (TGF)-β1 induces EMT in human neuroblastoma cells. Using quantitative RT-qPCR and western blot analyses, we found that the mRNA and protein expression levels of E-cadherin were significantly decreased, whereas that of α-SMA was significantly increased after neuroblastoma cells were treated with different concentrations of TGF-β1. A scratch test and Transwell migration assay revealed that cell migration significantly and directly correlated with the concentration of TGF-β1 indicating that TGF-β1 induced EMT in neuroblastoma cells and led to their migration. Inhibiting Smad2/3 expression did not affect the expression of the key molecules involved in EMT. Further investigation found that the expression of the glioblastoma transcription factor (Gli) significantly increased in TGF-β1-stimulated neuroblastoma cells undergoing EMT, accordingly, interfering with Gli1/2 expression inhibited TGF-β1-induced EMT in neuroblastoma cells. GANT61, which is a targeted inhibitor of Gli1 and Gli2, decreased cell viability and promoted cell apoptosis. Thus, TGF-β1 induced EMT in neuroblastoma cells to increase their migration. Specifically, EMT induced by TGF-β1 in neuroblastoma cells did not depend on the Smad signaling pathway, and the transcription factor Gli participated in TGF-β1-induced EMT independent of Smad signaling.

Smoothened Regulates Migration of Fibroblast-Like Synoviocytes in Rheumatoid Arthritis via Activation of Rho GTPase Signaling

Fibroblast-like synoviocytes (FLSs) acquire aggressive phenotypes characterized with enhanced migration abilities and inherent invasive qualities in rheumatoid arthritis (RA). Smoothened (Smo) is a key component of sonic hedgehog (Shh) signaling and contributes to tumor cell invasion and metastasis. The objective of this study is to investigate the role of Smo in the modulation of cell migration and explore the underlying molecular mechanism(s). FLSs were isolated from RA synovium. Shh levels were regulated by a Smo agonist (purmorphamine), Smo antagonist (KAAD-cyclopamine), or small interfering RNA targeting the Smo gene (Smo-siRNA) in RA-FLSs. Expression of Smo was detected by real-time PCR and western blot analysis. Cell migration was examined by Transwell assay and activation of Rho GTPases was measured by pull-down assays. Incubation with purmorphamine resulted in a significant increase of cell migration and activation of Rho GTPase signaling compared to controls (P < 0.05). However, treatment with KAAD-cyclopamine or transfection with Smo-siRNA suppressed migration of RA-FLSs and showed an inhibitory effect of Rho GTPase signaling. Together, these results suggest that Smo plays an important role in RA-FLSs migration through activation of Rho GTPase signaling and may contribute to progression of RA, thus, targeting Shh signal may have a therapeutic potential in patients with RA.

Hedgehog Pathway Inhibition Hampers Sphere and Holoclone Formation in Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common type of soft tissue sarcoma in children and can be divided into two main subtypes: embryonal (eRMS) and alveolar (aRMS). Among the cellular heterogeneity of tumors, the existence of a small fraction of cells called cancer stem cells (CSC), thought to be responsible for the onset and propagation of cancer, has been demonstrated in some neoplasia. Although the existence of CSC has been reported for eRMS, their existence in aRMS, the most malignant subtype, has not been demonstrated to date. Given the lack of suitable markers to identify this subpopulation in aRMS, we used cancer stem cell-enriched supracellular structures (spheres and holoclones) to study this subpopulation. This strategy allowed us to demonstrate the capacity of both aRMS and eRMS cells to form these structures and retain self-renewal capacity. Furthermore, cells contained in spheres and holoclones showed significant Hedgehog pathway induction, the inhibition of which (pharmacologic or genetic) impairs the formation of both holoclones and spheres. Our findings point to a crucial role of this pathway in the maintenance of these structures and suggest that Hedgehog pathway targeting in CSC may have great potential in preventing local relapses and metastases.

Chronic inflammatory airway diseases: the central role of the epithelium revisited

The respiratory epithelium plays a critical role for the maintenance of airway integrity and defense against inhaled particles. Physical barrier provided by apical junctions and mucociliary clearance clears inhaled pathogens, allergens or toxics, to prevent continuous stimulation of adaptive immune responses. The "chemical barrier", consisting of several anti-microbial factors such as lysozyme and lactoferrin, constitutes another protective mechanism of the mucosae against external aggressions before adaptive immune response starts. The reconstruction of damaged respiratory epithelium is crucial to restore this barrier. This review examines the role of the airway epithelium through recent advances in health and chronic inflammatory diseases in the lower conducting airways (in asthma and chronic obstructive pulmonary disease). Better understanding of normal and altered epithelial functions continuously provides new insights into the physiopathology of chronic airway diseases and should help to identify new epithelial-targeted therapies.